45.44. pg_trigger

The catalog pg_trigger stores triggers on tables and views. See CREATE TRIGGER for more information.

Table 45-44. pg_trigger Columns

Name Type References Description
tgrelid oid pg_class.oid The table this trigger is on
tgname name Trigger name (must be unique among triggers of same table)
tgfoid oid pg_proc.oid The function to be called
tgtype int2 Bit mask identifying trigger firing conditions
tgenabled char Controls in which session_replication_role modes the trigger fires. O = trigger fires in "origin" and "local" modes, D = trigger is disabled, R = trigger fires in "replica" mode, A = trigger fires always.
tgisinternal bool True if trigger is internally generated (usually, to enforce the constraint identified by tgconstraint)
tgconstrrelid oid pg_class.oid The table referenced by a referential integrity constraint
tgconstrindid oid pg_class.oid The index supporting a unique, primary key, or referential integrity constraint
tgconstraint oid pg_constraint.oid The pg_constraint entry associated with the trigger, if any
tgdeferrable bool True if constraint trigger is deferrable
tginitdeferred bool True if constraint trigger is initially deferred
tgnargs int2 Number of argument strings passed to trigger function
tgattr int2vector pg_attribute.attnum Column numbers, if trigger is column-specific; otherwise an empty array
tgargs bytea Argument strings to pass to trigger, each NULL-terminated
tgqual pg_node_tree Expression tree (in nodeToString() representation) for the trigger's WHEN condition, or null if none

Currently, column-specific triggering is supported only for UPDATE events, and so tgattr is relevant only for that event type. tgtype might contain bits for other event types as well, but those are presumed to be table-wide regardless of what is in tgattr.

Note: When tgconstraint is nonzero, tgconstrrelid, tgconstrindid, tgdeferrable, and tginitdeferred are largely redundant with the referenced pg_constraint entry. However, it is possible for a non-deferrable trigger to be associated with a deferrable constraint: foreign key constraints can have some deferrable and some non-deferrable triggers.

Note: pg_class.relhastriggers must be true if a relation has any triggers in this catalog.

copyright  ©  April 24 2015 sean dreilinger url: http://durak.org/sean/pubs/software/postgresql/catalog-pg-trigger.html